<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>伪元素和伪类的使用</title>
    <style>
        body,html {
            width: 100%;
            height: 100%;
        }
        .page-container{
            width: 100%;
            height: 100%;
            background: azure;
        }
        .page-container .box{
            width: 200px;
            height: 100px;
            background: aqua;
        }
        .box::before {
            display: block;
            content: '这里是before'
        }
        .box::after {
            display: block;
            content: '这里是after'
        }
        .inline-box{
            width: 50px;
            height: 50px;
            background: red;
        }
    </style>
</head>
<body>
    <div class="page-container">
        <h3>伪元素</h3>
        <span>hhh</span>
        <div class="box">
            我也有内容
            <div class="inline-box"></div>
        </div>
    </div>
</body>
</html>
